(a) Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly, to a liquid crystal display having a plurality of pixel areas divided into a number of domains to obtain a wide viewing angle.
(b) Description of the Related Art
In general, a liquid crystal display has an upper panel including a common electrode and a plurality of color filters, a lower panel including a plurality of thin film transistors and pixel electrodes, and a liquid crystal layer having liquid crystal molecules therebetween. The pixel electrodes and the common electrode are applied with electrical voltages to generate an electric field to vary the arrangement of the liquid crystal molecules, thereby controlling the transmittance of light passing through the liquid crystal layer. Since a pair of polarizers are attached to the upper and the lower panels, respectively, the light incident on the liquid crystal layer after passing through one polarizer varies its polarization during its progress in the liquid crystal layer, and the resulting polarization of the light determines the transmittance of the light out of the other polarizer.
Conventional LCDs typically have narrow viewing angles. Various techniques for widening the viewing angle have been developed. One of the techniques is to align the liquid crystal molecules perpendicular to the upper and the lower panels, and to form apertures or protrusions in the pixel electrodes and the common electrode opposite to the pixel electrodes.
The technique related to the apertures is to control the tilt directions of the liquid crystal molecules by using the fringe field generated by the apertures for widening the viewing angle.
The technique related to the protrusions is to control the tilt directions of the liquid crystal molecules by altering the electrical field using the protrusions.
Another technique is to provide the apertures in the pixel electrodes of the lower panel and the protrusions on the common electrode of the upper panel for controlling the tilt directions of the liquid crystal molecules.
These mentioned techniques to obtain a wide viewing angle are to provide a plurality of domains wherein most of the liquid crystal molecules in each domain are aligned in the same direction. The domain has two long sides and two short sides for improving the fringe field effect and the response time. However, in these liquid crystal displays, there are disadvantages in that the image quality is deteriorated because of the texture which departs from the short sides and deeply penetrate into the center of domains, and from overshoot of brightness that appear more brightly in the first stage of every frame on a screen. Thus it is desirable to reduce generation of the textures and to prevent the overshoot of brightness, thereby enhancing the image quality of a liquid crystal display.
A liquid crystal display is provided, which includes: a first substrate; a first signal line formed on the first substrate and extending in a direction; a second signal line intersecting but insulated from the first signal line; a pixel electrode formed in a pixel area defined by intersections of the first signal line and the second signal line, the pixel electrode having a plurality of partitions; a switching element connected to the first signal line, the second signal line, and the pixel electrode; a second substrate opposite the first substrate; a black matrix formed on the second substrate; and a common electrode formed over the second substrate having a plurality of domain defining members, wherein each domain is enclosed by the partitions of the pixel electrode and the domain defining members and has at least one long side parallel or perpendicular to the first signal line and at least one short side curved at an angle of about 30 to about 60 degrees with the first signal line.
According to an aspect of the present invention, the pixel electrode is made of such as ITO (indium tin oxide) or IZO (indium zinc oxide). Each of the plurality of the partitions has a rectangular shape and includes at least one chamfered corner or at least one convex corner. Each of the plurality of the partitions is arranged in the same direction as the second signal line. The plurality of partitions are connected by connecting members therebetween. The black matrix is made of a double-layered structure of Cr/CrO2.
According to a preferred embodiment of the present invention, a plurality of storage electrodes are further included between each of the plurality of partitions of the pixel electrode.
According to an aspect of the present invention, the plurality of domain defining members include a plurality of apertures. Each of the plurality of apertures has at least one end part shaped triangle. The triangle has an angle made by the bottom side and both lateral sides of the triangle in the range of about 30xc2x0 to about 60xc2x0. The plurality of domain defining members include a plurality of protrusions.
According to an aspect of the present invention, a liquid crystal layer is further included between the first substrate and the second substrate.
A liquid crystal display is also provided, which includes: a first panel including a first signal line, a second signal line intersecting the first signal line, a pixel electrode having a plurality of partitions, and a thin film transistor, wherein the thin film transistor includes a gate electrode extended from the first signal line, a source electrode extended from the second signal line, and a drain electrode connected to the pixel electrode, wherein the pixel electrode is formed in a pixel area defined by intersections of the first signal line and the second signal line; and a second panel disposed opposite the first panel, the second panel including a common electrode having a plurality of domain defining members, each of the plurality of domain defining members having at least one end portion shaped substantially as a triangle.
According to an aspect of the present invention, a liquid crystal layer is further included between the first panel and the second panel and a black matrix is further included on the second panel to define the pixel area.